1. Field of the Invention
The present invention relates to a facsimile machine for recording transmitted or copied images on cut sheets. More particularly, the present invention relates to a facsimile machine of a type which temporarily stores, in a memory, image data representative of the images desired to be recorded, before performing a recording operation with the image data onto cut sheets.
2. Description of the Related Art
Conventionally, a typical facsimile machine is capable of transmission and reception. During transmission, a document is read by a reading unit, the image decoded and then transmitted. During reception, received image data are stored in an image data memory, decoded, developed into record data (dot data) and then stored in a record data memory. The record data are sequentially retrieved from the record data memory, and recorded in line increments on a recording paper such as a cut sheet or a roll of thermal paper.
Conventional facsimile machines can record at several different speeds. A facsimile machine receives image data from a remote facsimile machine at a transmission speed corresponding to the recording speed selected at the facsimile machine.
A facsimile machine which uses cut sheets as the recording paper can be equipped to accommodate, for example, legal size sheets (with a length of about 376 mm), A4 size sheets (with a length of about 297 mm), or letter size sheets (with a length of about 279 mm). Assume now that the transmitted document is on sheets the same size as the sheet on which the document is to be recorded, for example, both A4 size sheets. Several pages worth of image data of the transmitted document are first stored in an image data memory. Image data are then retrieved from the image data memory to be decoded and developed into record data, at one-line increments. The thus-prepared line record data are stored in a record data memory. A cut sheet is supplied to a recording unit of the facsimile machine and transported there through at a predetermined pitch for every line increment of the record data retrieved from the record data memory and recorded on the sheet. When the entire sheet is recorded on, recording processes of the facsimile machine are interrupted, the sheet in the recording unit is discharged onto a discharged sheet tray of the facsimile machine, and a new cut sheet is supplied to the recording unit.
However, sometimes the length of one page worth of incoming image data is larger than the cut sheet set in the device. This can be caused by many reasons, such as the differences between different countries in set sizes for sheets (for example, legal size and A4 size), by the slant of the transmitted document, and the presence of a header at the top of the document. When the transmitted document is a larger sheet than the sheet on which the received image data of the transmitted document is to be recorded, for example, when the document is on a legal sized sheet and the record sheet is a letter sized sheet, the amount of image data contained in the document is greater than the amount of image data that can be recorded on the record sheet. As a result, image data from one page of the transmitted document is divided into two parts with each part being recorded on a different record sheet. When one page of incoming image data is divided in this way, recording processes are interrupted in order to allow discharge of the fully recorded sheet and supply of a new sheet.
When the size of the copied or transmitted document is greater than the size of the record sheet as described above, a facsimile machine which uses a cut sheet as the record sheet will divide one page worth of image data from the document into two parts which are recorded separately on two records sheets. As a result, recording processes are interrupted, and unnecessary sheet discharge and sheet supply processes are performed. While the recorded sheet is being discharged, the image data memory continues receiving incoming image data. Therefore, the amount of data put into the image data memory becomes greater than the amount taken out therefrom for recording processes. As a result, the amount of data stored in the image data memory will increase until finally the image data memory will fill up.
When the facsimile machine is not provided with an error correction mode (ECM) function, the full image data memory will cause a transmission error because flow control of transmission of the image data can not be performed. Therefore, the full image data memory will cause reception of incoming image data to be cut off.
Printing one sheet worth of document data on two record sheets also wastes paper. To avoid wasting paper in this manner, there has been known a facsimile machine of a type which contains an automatic function for calculating a reduction rate according to the length of the incoming image data (length of the transmitted document) and the size of the record sheet on which the incoming image data is to be recorded. The incoming data is then recorded on the record sheet according to calculated reduction rate. In this type of facsimile machine, the number of lines making up one page of incoming must be known in order to calculate the reduction rate for recording the incoming image data. Therefore, recording operations can not be started until one page worth of data has been completely received. Also, because the processing speed for recording operations (including sheet supply, recording, and sheet discharge) is slower than the processing speed for storing incoming image data in an image data memory (reception buffer), when data for a plurality of pages are received, there is a possibility that the capacity of the image data memory might be insufficient. The reduction function stops when the image data memory cannot sufficiently handle the amount of incoming image data. When this happens, received image data will be recorded on a record sheet without being reduced, or the error lamp will illuminate and reception processes will stop. If received data is recorded on the cut sheet without being reduced, the number of lines of data possible are recorded on the cut sheet but the rest of the data is ignored when the length of the data exceeds the size of the cut sheet. (However, this is not a problem when the length of the received data does not exceed the size of the cut sheet.) Also, reception efficiency drops when the error lamp illuminates and reception processes stop because the image data memory or reception buffer can not hold sufficient data.